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In this study, amylose- and cellulose-phenylcarbamate-based chiral columns with different chiral-selector (CS) chemistries were compared to each other for the separation of enantiomers of basic chiral analytes in acetonitrile and aqueous-acetonitrile mobile phases in HPLC. For two chemistries the amylose-based columns with coated and immobilized CSs were also compared. The comparison of CSs containing only electron-donating or electron-withdrawing substituents with those containing both electron-donating and electron-withdrawing substituents showed opposite results for the studied set of chiral analytes in the case of amylose and cellulose derivatives. Along with the chemistry of CS the focus was on the behavior of polysaccharide phenylcarbamates in acetonitrile versus aqueous acetonitrile as eluents. In agreement with earlier results, it was found that in contrast to the commonly accepted view, polysaccharide phenylcarbamates do not behave as typical reversed-phase materials for basic analytes either. In the range of water content in the mobile phase of up to 20-30% v/v the behavior of these CSs is similar to hydrophilic interaction liquid chromatography (HILIC)-type adsorbents. This means that with increasing water content in the mobile phase up to 20-30% v/v, the retention of analytes mostly decreases. The important finding of this study is that the separation efficiency improves for most analytes when switching from pure acetonitrile to aqueous acetonitrile. Therefore, in spite of reduced retention, the separation of enantiomers improves and thus, the HILIC-range of mobile phase composition, offering shorter analysis time and better peak resolution, is advantageous over pure polar-organic solvent mode. Interesting examples of enantiomer elution order (EEO) reversal were observed for some analytes based on the content of water in the mobile phase on Lux Cellulose-1 and Lux Amylose-2 columns., Competing Interests: Declaration of Competing Interest None., (Copyright © 2020 Elsevier B.V. All rights reserved.)

P-glycoprotein (P-gp) largely influences the pharmacokinetics (PK) and toxicities of xenobiotics in a patient-specific manner so that personalized drug scheduling may lead to significant patient's benefit. This systems pharmacology study investigated P-gp activity in mice according to organ, sex, feeding status, and circadian time. Sex-specific circadian changes were found in P-gp ileum mRNA and protein levels, circadian amplitudes being larger in females as compared to males. Plasma, ileum and liver concentrations of talinolol, a pure P-gp substrate, significantly differed according to sex, feeding and circadian timing. A physiologically-based PK model was designed to recapitulate these datasets. Estimated mesors (rhythm-adjusted mean) of ileum and hepatic P-gp activity were higher in males as compared to females. Circadian amplitudes were consistently higher in females and circadian maxima varied by up to 10 h with respect to sex. Fasting increased P-gp activity mesor and dampened its rhythm. Ex-vivo bioluminescence recordings of ileum mucosae from transgenic mice revealed endogenous circadian rhythms of P-gp protein expression with a shorter period, larger amplitude, and phase delay in females as compared to males. Importantly, this study provided model structure and parameter estimates to refine PK models of any P-gp substrate to account for sex, feeding and circadian rhythms.

This paper presents an application of high performance liquid chromatography coupled with quadrupole orbitrap high-resolution mass spectrometry (HPLC-Q-Orbitrap HRMS) for the analysis of 27 β-blockers and metabolites in milk powder. Homogenized milk power samples were extracted by acetonitrile and purified by using Oasis PRiME HLB solid-phase extraction cartridges. The Ascentis ® C8 chromatographic column was used to separate the analytes. The quantification was achieved by using matrix-matched standard calibration curves with carazolol-d₇ and propranolol-d₇ as the internal standards. The results show an exceptional linear relationship with the concentrations of analytes over wide concentration ranges (0.5⁻500 μg kg -1 ) as all the fitting coefficients of determination r² are > 0.995. All the limits of detection (LODs) and quantitation (LOQs) values were within the respective range of 0.2⁻1.5 μg kg -1 and 0.5⁻5.0 μg kg -1 . Overall average recoveries were able to reach 66.1⁻100.4% with the intra- and inter-day variability under 10%. This method has been successfully applied to the screening of β-blockers and metabolites in commercial milk powders. At the same time, the corresponding characteristic fragmentation behavior of the 27 compounds was explored. The characteristic product ions were determined and applied to the actual samples screening.

Herein we present the enantioseparation of 10 cardiovascular agents and six bronchiectasis drugs including propranolol, carteolol, metoprolol, atenolol, pindolol, esmolol, bisoprolol, bevantolol, arotinolol, sotalol, clenbuterol, procaterol, bambuterol, tranterol, salbutamol and terbutaline sulfate using carboxymethyl-β-cyclodextrin (CM-β-CD) as chiral selector. To our knowledge, there is no literature about using CM-β-CD for separating carteolol, esmolol, bisoprolol, bevantolol, arotinolol, procaterol, bambuterol and tranterol. During the course of work, changes in pH, CM-β-CD concentration, buffer type and concentration were studied in relation to chiral resolution. Excellent enantiomeric separations were obtained for all 16 compounds, especially for procaterol. An impressive resolution value, up to 17.10, was obtained. In particular, most of them achieved rapid separations within 20 min. Given the fact that enantioseparation results rely on analytes' structural characters, the possible separation mechanisms were discussed. In addition, in order to obtain faster separation for propranolol enantiomers in practical application, the effective length of capillary was innovatively shortened from 45 to 30 cm. After the validation, the method was successfully applied to the enantiomeric purity determination of propranolol in the formulation of drug substances., (Copyright © 2017 John Wiley & Sons, Ltd.)

Beta adrenergic antagonists like carvedilol are typical environmental pollutants detected in wastewater and surface water. Human metabolism of carvedilol is well investigated, while its environmental fates are still unknown. In recent years, there have been appearing reports on high toxicity of β-blockers toward aquatic organisms. In this paper the ability of the filamentous fungus C. echinulata to eliminate the β-blocker has been described for the first time. An 83% loss of carvedilol was observed after 120 h incubation of the tested fungus with the compound, where hydroxylated carvedilol metabolites were identified as the major biotransformation products. Carvedilol degradation by C. echinulata was proceeded by hydroxylation and conjugation reactions similar to its mammalian metabolism. Glucose conjugate was found in the fungi cultures, whereas glucuronide conjugates were detected in mammals. The impact of carvedilol on the functionality of fungal cells was also evaluated. A 2-fold decrease in the PC/PE ratio was noticed in the C. echinulata cell membrane after the exposition to carvedilol compared to control mycelium incubated without the β-blocker. The change can denote perturbation of fungal cell membrane integration by carvedilol. Moreover, 2.8-fold lower toxicity of postcultures supernatants toward D. magna were shown in contrast to abiotic control., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

Solid-state nuclear magnetic resonance (ssNMR) is a powerful and unique method for analyzing solid forms of the active pharmaceutical ingredients (APIs) directly in their original formulations. Unfortunately, despite their wide range of application, the ssNMR experiments often suffer from low sensitivity and peaks overlapping between API and excipients. To overcome these limitations, the crosspolarization inversion recovery method was successfully used. The differences in the spin-lattice relaxation time constants for hydrogen atoms T1(H) between API and excipients were employed in order to separate and discriminate their peaks in ssNMR spectra as well as to increase the intensity of API signals in low-dose formulations. The versatility of this method was demonstrated by different examples, including the excipients mixture and commercial solid dosage forms (e.g. granules and tablets)., (Copyright © 2016 Elsevier B.V. All rights reserved.)

Two chromatgraphic methods were developed for determination of Paracetamol (PCM) and Pamabrom (PAM) in presence of P-aminophenol (PAP) and Theophylline (THEO) as potential impurities of both drugs respectively. First method is HPTLC which depends on separation and quantitation of the studied drugs on aluminum plates pre-coated with silica gel 60 F₂₅₄ as a stationary phase using chloroform:methanol:ethyl acetate:glacial acetic acid (8:0.8:0.6:0.2, v/v/v/v) as mobile phase followed by densitometric measurement of the bands at 254 nm. Second method is RP-HPLC which comprises separation of the studied drugs on a Phenomenex C8 column by gradient elution using mobile phase consisting of sodium dihydrogen phosphate buffer (0.05 M): methanol:acetonitrile (85:10:5, v/v/v) at a flow rate of 1 mL/min for first 7.5 min and (70:20:10, v/v/v) at a flow rate of 1.5 mL/min for the next 5 min. The proposed methods were successfully applied for determination of the potential impurities of PCM and PAM after resolving them from the pure drugs. The developed methods have been validated and proved to meet the requirements delineated by ICH guidelines with respect to linearity, accuracy, precision, specificity and robustness. The validated methods were successfully applied for determination of the studied drugs in their pharmaceutical formulation. The results were statistically compared to those obtained by the reported RP-HPLC method where no significant difference was found; indicating the ability of proposed methods to be used for routine quality control analysis of these drugs., (Copyright © 2015 Elsevier B.V. All rights reserved.)

A sensitive, selective and simple method for the simultaneous determination of carvedilol enantiomers in aqueous solution has been developed using stir bar sorptive extraction (SBSE) followed by high-performance liquid chromatography (HPLC) with ultraviolet (UV) detection. This method is based on the reaction of carvedilol enantiomers with (-)-menthyl chloroformate (MCF) after extraction by the SBSE method to produce diastereomeric derivatives. The separation was achieved by use of a C18 analytical column and the influence of mobile phase composition on the enantioseparation of carvedilol was studied. The applicability of two sorptive phases, poly(methyl methacrylate/ethyleneglycol dimethacrylate) (PA-EG) and polydimethylsiloxane, were tested for extraction of carvedilol enantiomers from aqueous samples. The obtained results showed excellent linear dynamic ranges and precisions for each of them. The least limit of detection for (S)- and (R)-carvedilol obtained 8 and 11 µg L(-1), respectively, using the PA-EG sorptive phase. Inter- and intra-mean recoveries were also satisfactory, ranging from 98 to 103%, with coefficient of variation in the range of 1-5% at three fortified levels using a PA-EG coated stir bar. The proposed SBSE (PA-EG)-MCF derivatization-HPLC-UV method was successfully applied to enantioselective analysis of carvedilol in water and pharmaceutical dosages, confirming the application of this method., (© The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.)

AZD9343 is a water-soluble gamma amino butyric acid (GABAB) agonist intended for symptomatic relief in gastroesophageal reflux disease (GERD) patients. The compound has good chemical stability in aqueous solutions, as well as in the solid state. Only one crystal modification has been observed to date. This polymorph is slightly hygroscopic (1.5% water uptake at 80% relative humidity (RH)), which is an improvement compared to the structurally similar agonist lesogaberan (AZD3355) which liquefies at 65% RH. Since the substance is very polar and lacks a UV chromophore, conventional separation and detection techniques cannot be used to characterize the substance and its impurities. The analytical techniques are described, focusing on the capillary electrophoresis method with indirect UV detection for assay and purity, the liquid chromatographic method for enantiomeric separation with derivatization with UV chromophore and three complementary nuclear magnetic resonance (NMR) approaches ((31)P-NMR, (13)C-NMR and (1)H-NMR) for impurities. For oral solutions, it was important to select the right concentration of phosphate buffer for the specific drug concentration and routinely use small additions of EDTA. I.V. solutions containing physiological saline as tonicity modifier could not be stored frozen at -20 °C. Properties of AZD9343 will be discussed in light of experiences from the structurally similar lesogaberan and (2R)-(3-amino-2-fluoropropyl)sulphinic acid (AFPSiA).

Non-porous C18 silica gel stationary phase (1 µm) was prepared and applied to chiral separation in pressurized capillary electrochromatography (pCEC) for the enantioseparation of various basic compounds. The non-porous silica particles (1 µm) were synthesized using modified St6ber method. C18 stationary phase (1 µm) was prepared by immobilization of chloro-dimethyl-octadecylsilane. Using carboxymethyl-β-cyclodextrin (CM-β-CD) as the chiral additive, the pCEC conditions including the content of acetonitrile (ACN), concentration of buffer, pH, the concentration of chiral additive and flow rate as well as applied voltage were investigated to obtain the optimal pCEC conditions for the separation of four basic chiral compounds. The column provided an efficiency of up to 190,000 plates/m. Bupropion hydrochloride, clenbuterol hydrochloride, metoprolol tartrate, and esmolol hydrochloride were baseline separated under the conditions of 5 mmol/L ammonium acetate buffer at pH 4. 0 with 20% (v/ v) acetonitrile, and 15 mmol/L CM-β-CD as the chiral additive. The applied voltage was 2 kV and flow rate was 0.03 mL/min with splitting ratio of 300:1. The resolution were 1.55, 2.82, 1. 69, 1. 70 for bupropion hydrochloride, clenbuterol hydrochloride, metoprolol tartrate, esmolol hydrochloride, respectively. The C18 coverage was improved by repeating silylation method. The synthesized 1 µm C18 packings have better mechanical strength and longer service life because of the special, non-porous structure. The column used in pCEC mode showed better separation of the racemates and a higher rate compared with those used in the capillary liquid chromatography (cLC) mode. This study provided an alternative way for the method of pCEC enantioseparation with chiral additives in the mobile phase and demonstrated the feasibility of micron particle stationary phase in chiral separation.

Spherical β-CD-silica hybrid materials have been prepared successfully by simple one-pot polymerization, which provide a new strategy to construct new type of HPLC chiral stationary phases. Various β-CD, ethane, triazinyl and 3,5-dimethylphenyl functional groups that can provide multiple interactions were introduced into the pore channels and pore wall framework of mesoporous materials, respectively. The materials towards some chiral, acidic, anilines and phenols compounds showed multiple chromatographic separation functions including racemic resolution, anion exchange and achiral separations with a typical feature of normal/reversed phase chromatography. Multi-tasking including racemic resolution and achiral separations for selected compounds were performed simultaneously on a chiral chromatographic column. The multifunctional character of materials arises from the multiple interactions including hydrophobic interaction, π-π interaction, anion exchange, inclusion interaction and hydrogen bonding interaction., (Copyright © 2015 Elsevier B.V. All rights reserved.)

A simple, rapid and sensitive method was developed using ZnO nanoparticle (ZnO-NP) amplified flow-injection chemiluminescence to detect carvedilol, a non-cardioselective β-blocker. It has been found that carvedilol strongly inhibits the chemiluminescence of luminol-H2O2 catalyzed by ZnO-NPs. Under optimum conditions, a linear working range for carvedilol concentrations from 5 × 10(-8) to 1.0 × 10(-6) mol L(-1) (r > 0.9894, n = 8) was obtained with a detection limit of 3.25 × 10(-9) mol L(-1). The relative standard deviation for 8 repetitive determinations was less than 2.9% and recoveries of 99% and 102% were obtained. ZnO-NPs were synthesized using a green mechanochemical route. Transmission electron microscopy and x-ray diffraction were used to characterize ZnO-NPs. The method was successfully applied to detect carvedilol in pharmaceutical formulations., (Copyright © 2014 Elsevier B.V. All rights reserved.)

Neonatal energy metabolism in calves has to adapt to extrauterine life and depends on colostrum feeding. The adrenergic and glucocorticoid systems are involved in postnatal maturation of pathways related to energy metabolism and calves show elevated plasma concentrations of cortisol and catecholamines during perinatal life. We tested the hypothesis that hepatic glucocorticoid receptors (GR) and α₁- and β₂-adrenergic receptors (AR) in neonatal calves are involved in adaptation of postnatal energy metabolism and that respective binding capacities depend on colostrum feeding. Calves were fed colostrum (CF; n=7) or a milk-based formula (FF; n=7) with similar nutrient content up to d 4 of life. Blood samples were taken daily before feeding and 2h after feeding on d 4 of life to measure metabolites and hormones related to energy metabolism in blood plasma. Liver tissue was obtained 2 h after feeding on d 4 to measure hepatic fat content and binding capacity of AR and GR. Maximal binding capacity and binding affinity were calculated by saturation binding assays using [(3)H]-prazosin and [(3)H]-CGP-12177 for determination of α₁- and β₂-AR and [(3)H]-dexamethasone for determination of GR in liver. Additional liver samples were taken to measure mRNA abundance of AR and GR, and of key enzymes related to hepatic glucose and lipid metabolism. Plasma concentrations of albumin, triacylglycerides, insulin-like growth factor I, leptin, and thyroid hormones changed until d 4 and all these variables except leptin and thyroid hormones responded to feed intake on d 4. Diet effects were determined for albumin, insulin-like growth factor I, leptin, and thyroid hormones. Binding capacity for GR was greater and for α₁-AR tended to be greater in CF than in FF calves. Binding affinities were in the same range for each receptor type. Gene expression of α₁-AR (ADRA1) tended to be lower in CF than FF calves. Binding capacity of GR was related to parameters of glucose and lipid metabolism, whereas β₂-AR binding capacity was negatively associated with glucose metabolism. In conclusion, our results indicate a dependence of GR and α₁-AR on milk feeding immediately after birth and point to an involvement of hepatic GR and AR in postnatal adaptation of glucose and lipid metabolism in calves., (Copyright © 2014 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.)

The current study evaluates the ultra high performance liquid chromatography (UHPLC) method for the quantification of talinolol in lipid-based formulations. A simple, rapid, reliable and precise reversed phase UHPLC method has been developed and validated according to the regulatory guidelines, which was composed of isocratic mobile phase; acetonitrile and phosphate buffer saline (pH 4.5) with a flow rate of 0.4 mL/min, and column HSS C18 (2.1 x 50 mm, 1.8 μm). The detection was carried out at 245 nm. The developed UHPLC method was found to be rapid (1.8 min run time), selective with high resolution of talinolol peak (0.88 min) from different lipid matrices and highly sensitive (limit of detection and lower limit of quantification were 0.14 ppm and 0.5 ppm, respectively). The linearity, accuracy and precision were determined as acceptable over the concentration range of 0.5-100 ppm for talinolol. The results showed that the proposed UHPLC method can be used for the estimation of talinolol in lipid-based formulation by indicating its purity and stability with no interference of excipients or related substances of active pharmaceutical ingredient.

Tienoxolol is a pharmacologically active molecule designed with the functional groups ketothiophene, alkyl benzoate and arylpropanolamine so as to combine a diuretic and a β-adrenoreceptor antagonist into a single molecule. Its degradation products generated in several stress media have been determined by high-pressure liquid chromatography (HPLC) coupled to a hybrid mass spectrometer with a triple quadrupole-linear trap. A Polaris(®) column with a C18-A stationary phase and a linear gradient mobile phase composed of a mixture of trifluoroacetic acid 1% (v/v) and acetonitrile allowed for optimal separation. Structural elucidation of the degradation products has been based on MS/MS techniques, by comparing their fragmentation patterns to the precursor's data. Up to seven degradation products of the active ingredient, resulting from hydrolysis, oxidation, dehydration and transamidation have been identified, covering a range of possible degradation pathways for derivatives with such functional groups. Kinetics have been studied to assess the molecule's shelf life and to identify the most important degradation factor., (Copyright © 2014 Elsevier B.V. All rights reserved.)

A novel, fast, sensitive, and specific capillary electrophoresis (CE) technique coupled to a diode array detector has been developed for the separation and simultaneous determination of carvedilol (CRV) and hydrochlorothiazide (HCT) in two combination formulations. The proposed method utilized a fused silica capillary (55 cm x75 microm id) and the background electrolyte solution phosphate buffer (12.5 mM, pH 7.4)-methanol (95+5, v/v). The separation was achieved at 30 kV applied voltage and 24 degree C. Atorvastatin (80 microg/mL) was chosen as the internal standard. The described method was linear over the range of 1-200 and 0.2-150 microg/mL for CRV and HCT, respectively. Intraday and interday RSD (n = 6) was < or =1.4%. The LOD values of CRV and HCT were 0.26 and 0.07 microg/mL, respectively. The validated CE method was successfully applied to the analysis of two commercial tablet dosage forms. Forced degradation studies were performed on bulk samples of the two drugs using thermal, photolytic, hydrolytic, and oxidative stress conditions, and the stressed samples were analyzed by the proposed method. Degradation products produced as a result of stress studies did not interfere with the determination of CRV and HCT; the assay could, therefore, be considered stability-indicating.

This paper describes the development and application of a multi-residue chiral liquid chromatography coupled with tandem mass spectrometry method for simultaneous enantiomeric profiling of 18 chiral pharmaceuticals and their active metabolites (belonging to several therapeutic classes including analgesics, psychiatric drugs, antibiotics, cardiovascular drugs and β-agonists) in surface water and wastewater. To the authors' knowledge, this is the first time an enantiomeric method including such a high number of pharmaceuticals and their metabolites has been reported. Some of the pharmaceuticals have never been studied before in environmental matrices. Among them are timolol, betaxolol, carazolol and clenbuterol. A monitoring programme of the Guadalquivir River basin (South Spain), including 24 sampling sites and five wastewater treatment plants along the basin, revealed that enantiomeric composition of studied pharmaceuticals is dependent on compound and sampling site. Several compounds such as ibuprofen, atenolol, sotalol and metoprolol were frequently found as racemic mixtures. On the other hand, fluoxetine, propranolol and albuterol were found to be enriched with one enantiomer. Such an outcome might be of significant environmental relevance as two enantiomers of the same chiral compound might reveal different ecotoxicity. For example, propranolol was enriched with S(-)-enantiomer, which is known to be more toxic to Pimephales promelas than R(+)-propranolol. Fluoxetine was found to be enriched with S(+)-enantiomer, which is more toxic to P. promelas than R(-)-fluoxetine.

Carvedilol ((2RS)-1-(9H-carbazol-4-yloxy)-3-[[2-(2-methoxyphenoxy)ethyl]amino]propan-2-ol), a β1-, β2-, and α1-adrenoreceptor blocker drug with antioxidant and antiproliferative effects, is indicated for treatment of hypertension, stable angina pectoris, and congestive heart failure. A profile of this drug substance is provided in this chapter and includes physical characteristics of Carvedilol (e.g., UV-vis, IR, NMR, and mass spectra). Details regarding the stability of Carvedilol in the solid state and solution phase are presented and methods of analysis (compendial and literature) are summarized. Furthermore, an account of the pharmacokinetics (ADME) and synthesis of Carvedilol are presented., (Copyright © 2013 Elsevier Inc. All rights reserved.)

Background: A simple, precise and sensitive HPLC method has been developed for simultaneous determination of carvedilol and losartan in human plasma and urine samples. The analytes were extracted by a dispersive liquid-liquid microextraction method. A mobile phase of 15 mM sodium dihydrogen phosphate buffer (pH 4.0)/acetonitrile/2-propanol (70/27.5/2.5, v/v/v) was used to separate the drugs using a Waters® ODS column (250 × 4.6 mm) and detected by a UV detector at 222 nm., Results: The developed method is selective for studied drugs possessing a linearity range of 0.1-1.0 and 0.05-0.75 µg/ml, respectively, for losartan and carvedilol with precision <15%. The accuracy is better than 15% and the mean recovery of carvedilol and losartan was 98.9 and 100.2% for plasma and 100.7 and 100.5% for urine samples, respectively., Conclusion: The developed method is applicable for therapeutic drug monitoring and PK analyses.

Single-walled carbon nanotubes (SWNT) are proposed as chiral selectors for separation of carvedilol stereoisomers beginning since its racemic mixture. The novel developed FIA-methodology employs a microcolumn (mC) packed with a few milligrams of SWNT which showed to be effective in S(-) and R(+) carvedilol separation. Attending to spectral properties of analytes, molecular fluorescence was employed in the detection step. Separation of carvedilol enantiomers was achieved in less than 70s with an acceptable resolution factor of 3.16. Variables that influence the chiral separation such as pH and composition of eluent solution, sample injection volume and flow rate, activation mode of NTs and mass of the same in column have been examined in detail. At optimal operational conditions, well repeatability was achieved using the same column for more than 100 injections, putting in evidence the stability of nanomaterial and the efficacy and versatility of the proposed FIA-configuration. The new methodology was successfully applied to S(-) and R(+) carvedilol quantification in pharmaceutical preparations, resulting an attractive alternative to traditional separative methods being fast, simple, using low cost instrumentation and producing scarce waste., (Copyright © 2012 Elsevier B.V. All rights reserved.)

A sensitive and stereospecific liquid chromatography-tandem mass spectrometry method for the quantitative determination of TWo8 enantiomers ((2RS)-1-(7-methoxy-1H-indol-4-yloxy)-3-(2-(2-methoxyphenoxy)ethylamino)-propan-2-ol) was developed and validated in rat serum and some tissues. Racemic TWo8 is a new chemical entity, and it has been shown to possess pharmacological activity in vivo. The assay involved the diastereomeric derivatization of racemic TWo8 with 2,3,4,6-tetra-O-acetyl-beta-glucopyranosyl isothiocyanate. The TWo8 diastereoisomers quantification was performed on a triple quadrupole mass spectrometer employing an electrospray ionization technique. The precursor to the product ion transition for TWo8 derivatives and for the internal standard (carbamazepine) was m/z 776.4 → 387.2 and 237.4 → 194.4, respectively. The assay was validated with a linear range of 10-2000 ng/ml of racemic TWo8. The inter-day precisions for (-)-(S)-TWo8 and (+)-(R)-TWo8 were 2.1% to 14.9% and 1.3% to 14.8%, respectively. The inter-day accuracy for (-)-(S)-TWo8 and (+)-(R)-TWo8 was within 86% to 114% and 91% to 114%, respectively. A pilot pharmacokinetic study of this new β-adrenolytic compound has shown that (-)-(S)-TWo8 is eliminated faster than its antipode. The terminal half-lives of (-)-(S)-TWo8 and (+)-(R)-TWo8 were 3.2 and 3.9 h, respectively. The compound distribution into different organs, evaluated in tissue homogenate samples following TWo8 intravenous administration, showed an enantioselective penetration of TWo8 enantiomers in the liver (p < 0.03), in the kidney (p < 0.001), and in the lungs (p < 0.05). The developed method using liquid chromatography-tandem mass spectrometry method with electrospray ionization could be employed for quantitative determination of compounds with similar structure., (Copyright © 2012 Wiley Periodicals, Inc.)

(13) C cross-polarization magic-angle spinning nuclear magnetic resonance (CPMAS NMR) spectroscopy was applied to the identification and characterization of carvedilol (1-(9H-carbazol-4-yloxy)-3-[2-(2-methoxyphenoxy)-ethylamino]-propan-2-ol) in pharmaceutical preparations. Solid-state spectra (standard linewidth and lack of signal multiplicity) of carvedilol indicate that its physical form is the same (freebase form II); no other polymorphic forms were detected. The spectra of excipients, recorded under the same conditions, were helpful in their identification. The differences in chemical shifts for tablets I-VI are insignificant and suggest that there are no strong intermolecular drug-excipient interactions. The drugs from six manufacturers contained the same amount (25 mg) of the active substance per tablet; however, tablets differ in size and thus in the concentration of carvedilol. An attempt at quantitation of carvedilol in the dosage forms was made. The cross-polarization kinetics and other measurement parameters affecting the intensity and reproducibility of the spectra were determined. The results revealed a satisfying relationship between the composition of the tablets and the intensity of selected NMR signals. The (13) C CPMAS NMR technique was found to provide accurate quantification of drugs without any chemical preparation, as shown by the particular case of carvedilol's solid formulations., (Copyright © 2012 Wiley Periodicals, Inc.)

Quantitative and qualitative high-resolution (HR) dependent and independent acquisition schemes on a QqTOF MS (with resolving power 20,000-40,000) were investigated for the analysis of pharmaceutical compounds in biological fluids. High-resolution selected reaction monitoring (HR-SRM) was found to be linear over three orders of magnitude for quantitative analysis of paracetamol in human plasma, offering a real alternative to triple quadrupole LC-SRM/MS. Metabolic stability of talinolol in microsomes was characterized by use of three different acquisition schemes: (i) information-dependent acquisition (IDA) with a TOF MS experiment as survey scan and product-ion scan as dependent scan; (ii) MS(ALL) by collecting TOF mass spectra with and without fragmentation by alternating the collision energy of the collision cell between a low (i.e., 10 eV) and high setting (i.e., 40 eV); and (iii) a novel independent acquisition mode referred to as "sequential window acquisition of all theoretical fragment-ion spectra" (SWATH) or "global precursor ions scan mode" (GPS) in which sequential precursor ions windows (typically 20 u) are used to collect the same spectrum precursor and fragment ions using a collision energy range. SWATH or GPS was found to be superior to IDA or MS(ALL) in combination with UHPLC for qualitative analysis but requires a rapidly acquiring mass spectrometer. Finally, the GPS concept was used for QUAL/QUAN analysis (i.e. integration of qualitative and quantitative analysis) of bosentan and its metabolites in urine over a concentration range from 5 to 2,500 ng mL(-1).

This work proposes a simple and sensitive solid substrate-room temperature phosphorimetry (SS-RTP) for the selective determination of carvedilol (CV). The method is based on the sensitizing effect of sodium dodecyl benzene sulphonate (SDBS) on CV to activate the oxidation between NaClO and amaranth, resulting in the intense quenching of room temperature phosphorescence (RTP) of the system. Compared with non-SDBS system, the reduction of phosphorescence intensity (ΔI(p)) with SDBS is 16.5 times higher and is directly proportional to the content of CV, covering a wide range 0.080-16.00 fg/spot. The regression equation of the working curve can be expressed as ΔI(p) = 0.7780 + 7.057 m(CV) (fg/spot) (correlation coefficient (r) = 0.9976, n = 8), with a detection limit (LD) of 0.020 fg/spot (corresponding concentration is 5.1 × 10(-14) g/mL, sample volume is 0.40 μL/spot). This sensitive method has also been applied to determine trace CV in human plasma and the results agreed with synchronous fluorimetry (SF). The activation energy (E) and rate constant (k) of this activating reaction were 69.04 kJ/mol and 3.580 × 10(-4) s(-1), respectively. The reaction mechanism is also discussed., (Copyright © 2011 John Wiley & Sons, Ltd.)

A reversed-phase high-performance liquid chromatographic method is developed and validated for the quantitative determination of talinolol and to characterize its degradation products. A very good resolution between peaks is achieved using a C18 column at 40°C. The mobile phase comprises of a mixture of acetonitrile and potassium dihydrogen orthophosphate buffer (pH 4.4) in the ratio of 27:73 (v/v). The method is validated with respect to linearity, accuracy, precision, robustness, and forced degradation studies, which further proved the stability indicating power. During the forced degradation studies, talinolol is observed to be labile to hydrolytic stress and thermal stress (in the solution form). However, it is stable to the oxidative, photolytic, and thermal stress (in the solid form). The degraded products formed are investigated by electrospray ionization (ESI), time-of-flight mass spectrometry, nuclear magnetic resonance, and infrared spectroscopy. A possible degradation pathway is outlined based on the results. The method is found to be sensitive with a detection limit of 0.125 μg/mL and a quantitation limit of 0.378 μg/mL. The method is also demonstrated to be robust, as it is resistant to small variations of chromatographic variables such as pH, mobile phase composition, flow rate, and column temperature.

A new, simple, sensitive luminescence methods for the determination of carvedilol have been developed and validated. Carvedilol was remarkably quenching the luminescence intensity of the Tb(III) ion in the new terbium complex with 1-butyl-4-hydroxy-2-oxo-1,2-dihydroquinoline-3-carboxylic acid-(4-methyl-pyridin-2-yl)-amide (R) in aqueous solutions containing urotropine buffer (pH 7.5) at lambda(ex) = 317 nm and lambda(em) = 545 nm. Under optimal conditions, the quenching of luminescence intensity was found to be proportional to the concentration of carvedilol in the range of 0.5-400 microg/mL. The detection limit was 0.16 microg/mL. This method was applied for the determination of carvedilol in tablets "Coryol".

A novel method for simultaneous determination of atenolol, metoprolol and esmolol was proposed by capillary electrophoresis (CE) separation and electrochemiluminescence (ECL) detection. Poly-β-cyclodextrin (Poly-β-CD) was used as an additive in the running buffer to improve the separation of three analytes. The conditions for CE separation, ECL detection and effect of Poly-β-CD were investigated in detail. The three β-blockers with very similar structures were well separated and detected under the optimum conditions. The linear ranges of the standard solution for atenolol and esmolol were 2.5-125 μmol/L with a detection limit (S/N=3) of 0.5 μmol/L, and for metoprolol was 0.5-25 μmol/L with a detection limit of 0.1 μmol/L. For three β-blockers from spiked aqueous and urine samples, the accuracy and precision including intraday and interday experiments were performed by calculating the recovery, the relative standard deviations of the ECL intensity and the migration time, respectively. The developed method was applied to the determination of metoprolol content in commercial pharmaceutical, and the analytical results are in good agreement with the nominal value with recoveries in the range of 98.7-105%. The proposed method was also applied to the monitoring of pharmacokinetics for metoprolol in human body., (Crown Copyright © 2011. Published by Elsevier B.V. All rights reserved.)

A new colorimetric chiral sensor material consisting of three different functional sites such as chromophore (2,4-dinitrophenylazophenol dye), binding site (crown ether), and chiral barrier (3,3'-diphenyl-1,1'-binaphthyl group) was prepared and applied to the recognition of the two enantiomers of primary amino alcohols and amines. Among five primary amino alcohols and two primary amines tested, the two enantiomers of phenylalaninol show the highest difference in the absorption maximum wavelength (Δλ(max)=43.5 nm) and in the association constants (K(S)/K(R)=2.51) upon complexation with the colorimetric chiral sensor material and, consequently, the two enantiomers of phenylalaninol were clearly distinguished from each other by the color difference., (Copyright © 2010 Wiley-Liss, Inc.)

Chromoliths can be used at flow rates beyond those feasible for conventional microparticulate packed columns. Ideally, the plots of the retention time versus the inverse of delivered flow rate should exhibit y-intercept of zero. However, significant positive deviations correlating with the solute polarity were observed for several compounds chromatographed with a Chromolith column, owing to the increased system pressure. Consequently, the dead time marker exhibits a smaller deviation, making the retention factors depend on the flow rate. Chromoliths are made of a silica-based monolith encapsulated within a PEEK tube, and should suffer larger stress with pressure than stainless steel columns, tending to inflate them and increase their volume. This decreases the linear velocity inside the column, and increases the retention at relatively low pressure (<200 bar). In contrast, frictional heating, which is an issue for microparticulate columns, seems to be less significant for the highly permeable Chromoliths. The usefulness of the retention time versus the inverse of the delivered flow rate plots to measure the deviations, whatever their origin, is shown. This allows the correction of the retention times to the ideal behaviour, where the retention factors are independent of the flow rate., (2010 Elsevier B.V. All rights reserved.)

The manuscript concerns the development and validation of a method for enantiomeric analysis of structurally related amphetamines (amphetamine, methamphetamine, 4-methylenedioxymethamphetamine (MDMA), 3,4-methylenedioxyamphetamine (MDA) and 3,4-methylenedioxy-N-ethylamphetamine (MDEA)), ephedrines (ephedrine, pseudoephedrine and norephedrine) and venlafaxine in wastewater by means of chiral chromatography coupled with tandem mass spectrometry. Solid-phase extraction on Oasis HLB sorbent used for sample clean-up and concentration of analytes resulted in very good recoveries accounting for >70%. Signal suppression during MS analysis was negligible for most studied analytes. Resolution of enantiomers of chiral drugs was found to be higher than 1. Preliminary assay validation was undertaken. The mean correlation coefficients of the calibration curves, which were on average higher than 0.997 for all studied analytes, showed good linearity of the method in the studied range. Intra- and inter-day repeatabilities were on average less than 5%. The method quantification limits in wastewater were at low ppt levels and varied from 2.25 to 11.75ng/L. The method was successfully applied for the analysis of raw and treated wastewater samples collected from four wastewater treatment plants. A common occurrence of 1R,2S (-)-ephedrine, 1S,2S (+)-pseudoephedrine and venlafaxine in both raw and treated wastewater samples was observed. Amphetamine, methamphetamine, MDMA and MDEA were also detected in several wastewater samples. The study of enantiomeric fractions of these chiral drugs proved their variable non-racemic composition. The influence of wastewater treatment processes on the enantiomeric composition of chiral drugs was also noted and might indicate enantioselective processes occurring during treatment, although more comprehensive research has to be undertaken to support this hypothesis., (Copyright 2010 Elsevier B.V. All rights reserved.)

Simple, rapid, and selective RP-HPLC methods with UV detection were developed for simultaneous determination of chlordiazepoxide hydrochloride and mebeverine hydrochloride (Mixture I) and carvedilol and hydrochlorothiazide (Mixture II). The chromatographic separation in both mixtures was achieved by using an RP-C8 (octylsilyl) analytical column. For Mixture I, a mobile phase composed of acetonitrile-0.05 M disodium hydrogen phosphate-triethylamine (50 + 50 + 0.2, v/v/v), pH 2.5, was used; the detector wavelength was 247 nm. For Mixture II, the mobile phase consisted of acetonitrile-0.05 M disodium hydrogen phosphate (50 + 50, v/v), pH 4.0, and the detector was set at 220 nm. Quantification of the analytes was based on measuring their peak areas. Both mixtures were resolved in less than 6 min. The reliability and analytical performance of the proposed HPLC procedures were statistically validated with respect to linearity, range, precision, accuracy, selectivity, robustness, LOD, and LOQ. The linear dynamic ranges were 2.5-150 and 2.5-500 microg/mL for chlordiazepoxide HCI and mebeverine HCI, respectively, and 0.25-200 and 0.25-150 microg/mL for carvedilol and hydrochlorothiazide, respectively. The validated HPLC methods were successfully applied to the analysis of their commercial tablet dosage forms, for which no interfering peaks were encountered from common pharmaceutical adjuvants.

Background: Harmonization of results allows a more effective utilization of laboratory tests; we verified the feasibility of harmonizing serum alkaline phosphatase results by two methods., Methods: Patient sera (n=106) and candidate calibration materials (n=8) were analyzed by two methods, employing either diethanolamine (DEA) or 2-amino-2-methyl-1-propanol (AMP) as phosphate-accepting buffers. Results for patient sera by the DEA method were recalculated, with either a commutable or a non-commutable calibration material, both with values assigned by the AMP method., Results: After calibration with the commutable material, the median intermethod difference (DEA-AMP) and ratio (DEA/AMP) dropped from 195 U/l to 0 U/l and from 2.47 to 1.00, respectively. When a non-commutable material was used the former became 124 U/l and the latter 1.94. After recalibration with the commutable material, linear regression and correlation analysis of DEA vs AMP values for the set of 106 patient sera gave: intercept=0.8 U/l; slope=0.997; and nonparametric correlation coefficient r=0.9995., Conclusions: Harmonization of alkaline phosphatase results by AMP and DEA methods is feasible when commutable calibration materials are used in the trueness transfer process., (Copyright 2010 Elsevier B.V. All rights reserved.)

The influence of the BGE composition, including the addition of a single-isomer sulfated beta-CD derivative, on the ionization performance of the model compound carvedilol in NACE-ESI-MS was studied using an alternative infusion method. This approach employs voltage-induced infusion of the BGE containing the analyte, and takes into account the effects of variations in EOF and effective analyte mobility on the ESI-MS intensity. First, the optimal composition of the sheath liquid for CE-MS in terms of signal abundance and stability was determined. The BGE ammonium formate, acetate, and camphorsulfonate were found to have similar effects on analyte ionization. Addition of single-isomer sulfated beta-CD derivatives (available as sodium salt) to the BGE revealed that the anionic CD derivatives did not give rise to the same ionization suppression effect. This result can be attributed to differences in the dissociation state of these sodium salts. Finally, it is shown that information about chiral selectivity can also be obtained with the applied infusion method.

The method is presented to analyze azaperone and carazolol in pigs kidney. Samples were extracted with acetonitryle. The determination was performed by LC-ESI-MS/MS. The LC was equipped with column Luna C18 Phenomenex. Haloperidol was used as internal standards. The method was validation according to the criteria of Decision Commission No 2002/657/EC. Recoveries for the level 100 microg/kg azaperone and 25 microg/kg carazolol were in the range 91.2-107.0% and 70.8-93.2%. The limit of decision (CCalpha) and detection capability (CCbeta) was respectively 125.9 microg/kg, 160.0 microg/kg for azaperone and 29.3 microg/kg, 33.3 microg/kg. LC-MS/MS technique fulfill the requirements of Decision Commission No 2002/657/EC.

A new method is presented for the determination of five selected beta-receptor antagonists by HPLC, which emphasizes sample preparation via retention on a new type of silica gel sorbent used for solid-phase extraction (SPE). Sorbents of this type were obtained by the chemical modification of silica gels of various porosities by cholesterol ligands. The cholesterol-based packing material was investigated by spectroscopic methods and elemental analysis. The recoveries obtained with the extraction procedure were optimum over a relatively broad sample pH range (3.08-7.50). Analytical factors such as the sample loading, the washing step and elution conditions, the concentration of beta-receptor antagonists to be extracted, and the type of sorbent were found to play significant roles in the sample preparation procedure and would therefore need to be controlled to achieve optimum recoveries of the analytes. Under optimum conditions, the recoveries of nadolol, acebutolol, esmolol, oxprenolol and propranolol from spiked buffers, blood and urine were reproducible and dependent on the polarity or hydrophilicity of the compounds. The above analytes were determined by reverse-phase high-performance liquid chromatography (HPLC) with UV and ESI-ion trap mass spectrometry (MS) detection. The described method was found to be suitable for the routine measurement of compounds that are both polar and basic, and can be applied for the analysis of biological samples such as urine and blood in clinical, toxicological or forensic laboratories. The recovery measurements were performed on spiked human urine and serum, and on real samples of mouse blood serum.

Carvedilol (CV) is an antagonist of alpha1 and beta1,beta2 membrane adrenoceptors and also a modulator of cardiac electrophysiological properties. It is widely prescribed for the treatment of cardiovascular diseases. During stability testing of CV solid dosage forms an unknown degradation product referred as UP, exceeded the identification thresholds of ICH Q3B guidelines. The HPLC analysis of the detected unknown product was performed by a newly, developed, specific and validated method, also suitable for the quantitative determination of the known CV impurities (imp B, C, E and F) and the other degradation products. The separation was achieved with an X-terra C18 column, using acetonitrile-phosphate buffer pH 2.5 as mobile phase. The isolation of UP was carried out by semi-preparative chromatography method, followed by deep freezing of the collected fractions until the organic and the aqueous phases were separated. Chromatographic behaviour of CV and UP was compared, in mobile phases of different pH and gave valuable information concerning the dissimilarities of their ionization. UP was further studied by MS and 1H NMR spectrometry, revealing structural similarities with the parent molecule. Finally, the unknown peak of degradation product was attributed to a new compound generated from the interaction of CV molecule and polyvinyl pyrrolidone (PVP) in the presence of water molecules. Moisture and temperature was proved to affect the formation of UP and its concentration in CV tablets. Appropriate modifications of the packaging of CV tablets can be made in order to reduce UP concentration down to the accepted levels, during the tablets' shelf life.

A novel flow injection (FI)-spectrofluorimetric methodology for the determination of carvedilol in microheterogeneous medium has been developed. In the sodium dodecyl sulfate (SDS) surfactant medium, an additional fluorescence enhancement was produced by the electrolyte NaCl. A total enhancement of 3.1-fold in the native fluorescent response was achieved respect to aqueous medium. Using an excitation and emission wavelength of 286 and 341 nm, respectively, a good linear relationship was obtained in the range of 9x10(-8) to 1x10(-6) mol L(-1) with a detection limit of 3.63x10(-9) mol L(-1) (S/N=3). This method was applied to determine carvedilol in commercial pharmaceutical formulations. Good concordance was found between the nominal (6.25, 12.5 and 25.0 mg) and experimental values. The new methodology developed showed high selectivity respect to the common excipients used in pharmaceuticals. The sampling rate was 30 samples h(-1). From the fluorescent properties, binding constant for carvedilol-SDS determined was 3.2x10(2) L mol(-1).

Performance evaluation of accurate mass measurement by the LTQ/Orbitrap, at a resolving power of 60,000 and in external calibration mode, indicated that the Orbitrap is capable of providing high mass accuracy of <2 ppm for over 24 h post-calibration. This, together with limited trade-off between sensitivity and resolving power plus a wide dynamic range for mass accuracy, suggested that the LTQ/Orbitrap is an ideal analytical tool for structural elucidation of metabolites. The application of the LTQ/Orbitrap to identification of human liver microsomal metabolites of carvedilol was evaluated, using parent mass list triggered data-dependent multiple-stage accurate mass analysis, at a resolving power of 60,000 in external calibration mode. A metabolite identification workflow was developed to utilize chemical formulas from high-resolution accurate mass measurements to confirm structures of product ions of a drug proposed by Mass Frontier, illustrated by identification of structures used to establish lineage of product ions of carvedilol, which later served as a template for identification of its metabolites. A total of 58 in vitro metabolites of carvedilol were detected using 5-ppm mass tolerance filters for theoretical m/z of protonated molecules of predicted metabolites in addition to product ions and neutral mass losses diagnostic of carvedilol. The chemical formulas with unsaturation numbers calculated from the accurate m/z of precursor and product ions can be used to assign, with a high degree of confidence, the structures of metabolites and the sites of metabolism. The mass accuracies obtained for all full scan MS and MSn spectra were <2 ppm. The majority of the metabolites identified agreed with those previously reported except for those that have not been reported before. For example, several glutathione conjugates of carvedilol were reported for the first time, which may explain the reported hepatotoxicity during clinical trials and recent clinical use., (Copyright (c) 2007 John Wiley & Sons, Ltd.)

Simple extraction-free spectrophotometric methods have been developed for the determination of carvedilol (CAR). The methods were based either on charge-transfer reaction of the drug with the sigma-acceptor iodine, in acetonitrile, or on ion-pair formation with the acidic sulphophthalein dyes bromothymol blue (BTB) and bromocresol green (BCG), in chloroform. The obtained complexes showed absorbance maxima at 363, 411 and 414 nm, respectively for iodine, BTB and BCG. Beer's law validation, accuracy, precision, and other aspects of analytical merit are presented in the text. The proposed methods were applied for the determination of CAR in tablets and compounded capsules. The results were in good agreement with those obtained by an established UV spectrophotometric method.

In this study, new and rapid stability indicating ultraviolet spectroscopic methods were developed and validated for the estimation of ezetimibe and carvedilol in pure form and in their respective formulations. Since both the drugs are poorly water soluble, 20% v/v acetonitrile in triple distilled water was selected as the solvent system for both the drugs. This ensured adequate drug solubility and maximum assay sensitivity. The linearity range for ezetimibe and carvedilol at their respective wavelength of detection of 232 nm and 238 nm was obtained as 2-50 microg/ml and 2-20 microg/ml respectively. The linear regression equations obtained by least square regression method, were Y = 0.0443 x (X) + 0.0106 for ezetimibe and Y = 0.1080 x (X) + 0.034 for carvedilol, where Y is the absorbance and X is the concentration (in microg/ml) of pure drug solution. The detection and quantitation limit as per the error propagation theory were found to be 0.4 microg/ml and 1.3 microg/ml respectively for ezetimibe and 0.7 microg/ml and 2.1 microg/ml respectively for carvedilol. The methods were employed with high degree of precision and accuracy for the estimation of total drug content in two commercial tablet formulations of each of the two drugs. It was concluded that both the developed methods are accurate, sensitive, precise, and reproducible. They can be applied directly for the estimation of drug content in pharmaceutical formulations.

Objective: To induce DNA oxidative damage in colorectal crypt cells by hydrogen peroxide in vitro., Methods: Hydrogen peroxide was diluted into 100, 50, 10, 5 and 1 micromol/L with RPMI 1640. Colorectal crypt cells were treated with peroxide for 10 min, 30 min, 1 h, 1.5 h, 12 h and 24 h respectively. The survival of colorectal crypt cell was measured by MTT method, and the DNA oxidative damage special product, 8-OhdG was detected with immunohistochemical staining. Liner regression was used to measure the time trend of survival rate with SPSS 10.0 software., Result: Survival rate of colorectal crypt cell was 60% and 80% after 10 min of hydrogen peroxide treatment. The longer treatment of hydrogen peroxide, the lower survival rate; the survival rate was reduced to 30% in 24 h. After 10 or 30 min treatment of 100 or 50 micromol/L hydrogen peroxide, the survival rates of colorectal crypt cells were reduced by 20% compared with those of 10, 5 and 1 micromol/L hydrogen peroxide. However, while cells were treated with different concentrations of hydrogen peroxide for 1.0 h or above, there were no differences in cell survival rates. The time trend test results demonstrated that the survival rates of colorectal crypt cells treated with 10, 5 and 1 micromol/L hydrogen peroxide were significantly decreased with the time length of treatment. Colorectal crypt cells treated with different concentrations of hydrogen peroxide for 15 minutes were positively stained brown in cytoplasm and nuclear by immunohistochemistry with 8-OhdG monoclonal antibody., Conclusion: Hydrogen peroxide could induce DNA oxidative damage in colorectal crypt cells. And treated with 1 - 10 micromol/L hydrogen peroxide for 10 - 30 min, DNA oxidative damage is apt to be induced in colorectal crypt cell.

A simple, accurate, precise, and sensitive kinetic spectrophotometric method for determination of befunolol hydrochloride is described. The method is based on the formation of a colored product with 4-chloro-7-nitro-2,1,3-benzoxadiazole (NBD-Cl) in methanol at 70 degrees C for 45 min. The red-colored product was measured at 523 nm. The optimization of various experimental conditions is described; Beer's law was obeyed in the range 15.25 x 10(-6) to 122.04 x 10(-6) M. The results obtained showed good recoveries (100.1 +/- 0.80%). Application of the proposed method to a pharmaceutical formulation was successfully achieved. The determination of befunolol hydrochloride by fixed time, fixed concentration, and rate constant methods was feasible with the calibration equation obtained. However, the fixed time method proved to be more applicable.

1-Aminopropanone (APR) is a volatile aminoketone of human origin that has been identified in raw sewage and surface waters. However, the traditional methodology for the determination of APR is extremely complicated and requires a skilled chemist to achieve consistent results. This investigation presents a novel and simple method for the analysis of APR by direct derivatization in aqueous media. APR is synthesized as its hydrochloride and derivatized using mercaptoethanol and o-phthalaldehyde. The product of reaction is separated on a 15 cm x 4.6 mm Luna C-18 column (1 mL/min, 45:55 acetonitrile: Water) and detected using a single quadrupole mass spectrometer detector operated in atmospheric pressure chemical ionization (APCI) mode. Method detection limits as low as 100 nM were routinely obtained with a precision of 1.7%. Recoveries of APR were always found to be greater then 88% in surface and wastewater samples fortified at three different levels. However, despite the robustness of the method and the fact that APR was consistently detected in urine it was not present in a variety surface or wastewaters analyzed during the course of the study. These results pose a critical question on the use of APR as a tracer for human derived wastewaters.

Evaluation of lipophilicity parameters for basic compounds using different chromatographic stationary phases is presented. An HPLC method for determination of lipophilic molecule-stationary phase interactions was based on gradient analysis. Differences in correlation between the lipophilicity of compounds and experimental chromatographic results obtained in pseudo-membrane systems showed a strong influence of stationary phase structure and physico-chemical properties. beta-Blocker drugs with varying lipophilicity and bio-activity were chosen as test compounds. The stationary phases used for the study were monolithic rod-structure C18 and silica gel octadecyl phase SG-C18 as reference material. The second group was silica gel-based polar-embedded alkylamide and cholesterolic phases. The mobile phase was composed of acetonitrile or methanol with ammonium acetate, and a linear gradient of methanol and acetonitrile in mobile phase was performed. A linear correlation of plots of log k(g) = f(log P) was observed, especially for polar-embedded phases, and this allowed log P(HPLC) to be calculated. The behavior of stationary phases in methanol and acetonitrile buffer showed differences between obtained log P(HPLC) values., ((c) 2005 John Wiley & Sons, Ltd.)

A sensitive and selective method for simultaneous determination of carvedilol and dopamine was described. The emission wavelengths of carvedilol and dopamine were at 354 nm and 314 nm with the excitation at 290 nm, respectively. The determination of carvedilol and dopamine by normal fluorometry was difficult because the emission spectra of carvedilol and dopamine were overlapped seriously. The first derivative peaks of carvedilol and dopamine were at 336 nm and 302 nm, respectively. The linear regression equations of the calibration graphs of carvedilol and dopamine were C = 0.000557H-0.00569 and C = 0.00438H-0.0812, with the correlation coefficients were 0.9953 and 0.9988, respectively. The liner range for the determination of carvedilol was 0.002 microg ml(-1) to 0.02 microg ml(-1), and 0.05 microg ml(-1) to 0.6 microg ml(-1) for dopamine. The detection limits were 1 ng ml(-1) for carvedilol and 0.04 microg ml(-1) for dopamine, respectively. The relative standard derivative (RSD) of 4.38% and 4.35% was observed for carvedilol and dopamine, respectively. The recovery of carvedilol was from 95.00% to 106.7% in human serum and from 97.50% to 105.0% in urine sample. The recovery of dopamine was from 100.0% to 102.5% in human serum and from 97.50% to 105.0% in urine sample. This method is simple and can be used for determination of carvedilol and dopamine in human serum and urine sample with satisfactory results.

Ultraviolet (UV) spectrophotometric and nonaqueous volumetric methods are described for the determination of carvedilol in pharmaceutical formulations. Linearity, precision, and accuracy were evaluated according to the validation guidelines of the International Conference on Harmonization and the United States Pharmacopeia for both methods. The UV spectrophotometric procedure was performed in ethanol at 244 nm. Good linearity was obtained between 2 and 7 microg/mL with a correlation coefficient of 0.9999. The intra- and interday precision values were <2% for all samples analyzed. The accuracy, determined from recovery studies, was between 97.5 and 102.2%. The other procedure was based on the volumetric quantitation of carvedilol in a nonaqueous medium with 0.01 M perchloric acid and 1% violet crystal as the indicator. The validation of the volumetric method yielded good results that included linearity (r of > 0.999), precision (relative standard deviations of <2% for intra- and interday precision), and accuracy (96.4-102.4%). The methods were applied to tablets and compounded capsules. Statistical analysis by analysis of variance showed no significant difference between the results obtained by the proposed methods.

A rapid and reliable high-performance liquid chromatographic method was developed and validated for the simultaneous determination of norephedrine (NE), norpseudoephedrine (NPE), ephedrine (E), pseudoephedrine (PE), methylephedrine (ME) and methylpseudoephedrine (MPE) in both a Mahwang traditional Chinese medicine (TCM) preparation and in urine using alpha-ethylbenzylamine as the internal standard. The method uses a Spherisorb C(18) column for an isocratic elution in a tetraethylammoniumphosphate-methanol mobile phase at a wavelength of 206 nm. The limits of detection of NE, NPE, E, PE, ME and MPE in sample solutions ranged from 0.1 to 0.3 microg[sol ]mL at a signal-to-noise ratio of 3. The within-day precision as calculated from the Mahwang TCM preparation and urine samples was below 6.2 and 1.4% for each analyte. The between-day precision as calculated from the Mahwang TCM preparation and urine samples was below 6.8 and 5.9% for each analyte. The between-day accuracy as determined from the Mahwang TCM preparation and urine samples was below 2.2 and 6.8% for each analyte. The recoveries for six compounds, obtained with compounds spiked into the Mahwang TCM preparation and urine, were found to be more than 93.6%. This method can be successfully applied to doping and excretion rate studies., ((c) 2005 John Wiley & Sons, Ltd.)

Soil and groundwater samples were collected at the site of a former chemical processing plant in areas impacted by accidental releases of MEA (monoethanolamine) and IPA (2-propanolamine or isopropanolamine). Although their use had ceased ca. 10 years before sample collection, soils collected at contamination sites had MEA concentrations ranging from ca. 400 to 3000 mg/kg and IPA concentrations from ca. 30 to 120 mg/kg. Even though alkanolamines are miscible in water, transport to groundwater was slow, apparently because they are present in soil as bound cations. Only one groundwater sample (near the most highly contaminated soil)from wells directly adjacentto and down-gradient from the contaminated soils had detectable MEA, and none had detectable IPA. However, ammonia was found in the soil samples collected in the MEA-contaminated areas (ca. 500-1400 mg/kg) and the groundwater (80-120 mg/L), as would be consistent with bacterial degradation of MEA to ammonia, followed by transport of ammonia into the groundwater. Counts for bacteria capable of using MEA or IPA as a sole carbon source were ca. 5 x 106 and 1 x 106 (respectively) per gram in uncontaminated site soil, but no such organisms were found in highly contaminated soils. Similarly, bacterial degradation of MEA in slurries of highly contaminated soils was slow, with ca. 8-20 days required for half of the initial concentrations of MEA to be degraded at 20 degrees C and 30-60 days at 10 degrees C. In contrast, bacterial degradation studies using uncontaminated site soils spiked with ca. 1300 mg/L either MEA or IPA showed very rapid degradation of both compounds,with more than 99% degradation occurring in less than 3 days with quantitative conversion to ammonia, followed by slower conversion to nitrite and nitrate. The results obtained in the site soils, the groundwater samples, and from the biodegradation studies demonstrate that MEA and IPA can persist for decades on soil at high (hundreds of mg/kg) concentrations without significant migration into groundwater, despite the fact that they are miscible in water. Since MEA and IPA exist primarily as cations at the pH of site soils, their persistence apparently results from strong binding to soil, as well as inhibition of natural bioremediation in highly contaminated field soils.

A sensitive and selective method for the simultaneous determination of carvedilol and ampicillin sodium (AS) in the presence of human serum albumin (HSA) is described. The maximum emission wavelengths of carvedilol and AS are at 357 nm and 426 nm with excitation at 254 nm, respectively. The first-derivative peaks of carvedilol and AS were at 337 nm and 398 nm, respectively. The linear-regression equations of the calibration graphs of carvedilol and AS were C = 0.0001H - 0.0063 and C = 1.530H - 43.84; the correlation coefficients were 0.9990 and 0.9986, respectively. The detection limits were 1 ng ml(-1) for carvedilol and 23 microg ml(-1) for AS, respectively. The effects of the pH, the stability of carvedilol and AS and foreign ions on the determination of carvedilol and AS were examined. The recoveries of carvedilol and AS were measured. This method is simple and can be used for the determination of carvedilol and AS in human serum and urine samples with satisfactory results.